US researchers find simpler way to process plant biomass

MADISON, Wis. — Engineers from the University of Wisconsin-Madison have come up with a new method to turn lignocellulosic biomass into liquid transportation fuel or into different chemicals, which significantly reduces the costs, the university website has announced.

A team of chemical and biological researchers at the university use a biomass-derived solvent in the process, which not only makes it cost-effective but also more streamlined. By adding the solvent, engineers no longer have to go through the required pretreatment steps, which separate the two key elements in plant biomass hemicellulose and cellulose and which account for a third of the costs in biofuel production. The pretreatment is necessary because the two components react at different rates.

James Dumesic and Michel Boudart, two of the authors of the research, which is published in the Energy and Environmental Science journal, reveal that the secret to the simultaneous processing of cellulose and hemicellulose is gamma-valerolactone, or GVL, which can be used as a cheap but at the same time energy-dense biofuel.

Dumesic explained that GVL is the perfect solvent for biomass conversion, as it is a conversion process product itself. If the solvent becomes a part of the process it can be much more efficient, compared to the present method that adds water but does not achieve great results, he said. What GVL achieves is broadening the conditions which allow for processing hemicellulose and cellulose, so that the optimal conditions overlap. As a result, engineers can process the two components simultaneously and produce furfural from hemicellulose and levulinic acid from cellulose.

Furfural is an important chemical solvent and it can also be used in the production of polymers and adhesives. Some 300,000 tons of furfural are used in the United States alone. Thanks to their discovery, engineers can now convert furfural to levulinic acid, a biochemical that can be used for solvents, fuel additives or GVL. Another advantage of GVL is that it facilitates the solubility of lignins and humins — materials that can often clog systems — and makes the whole process much more environmentally friendly. Dumesic says that GVL requires 10 times less sulfuric acid and this additionally reduces costs. Last, but not least, GVL works well with water, which means that wet biomass can also be processed, the researchers concluded.

Even though the research was conducted in the university''s laboratories, Dumesic is convinced the same process can be applied on a large scale. Currently, researchers are looking into how long GVL can be used in the process before it accumulates enough impurities to prevent the process. He adds that furfural, levulinic acid and GVL are all chemicals that have a series of practical applications, so simplifying the process and making it less expensive would bring significant benefits.

The research was funded by the Great Lakes Bioenergy Research Center at the University of Wisconsin-Madison and by the U. S. Defense Advanced Research Projects Agency, the university''s website said.